The present invention is related to disposable wiping articles, and more particularly to disposable wiping articles having distinct regions of increased caliper, and methods for their manufacture.
Disposable wiping articles are well known in the art. Such wiping articles typically have a substrate which includes one or more materials or layers. The substrate can be pre-moistened with a wetting agent prior to use, or alternatively, can be combined with a liquid at the point of use of the article. Pre-moistened wiping articles are also referred to as xe2x80x9cwet wipesxe2x80x9d and xe2x80x9ctowelettes.xe2x80x9d
Desirable features of such wiping articles include texture, caliper (thickness) and bulk (volume per unit weight). A relatively high value of texture is desirable for aiding in cleaning of surfaces. Relatively high values of caliper and bulk are desirable for providing volume in the article for receiving and containing liquids.
One method of imparting texture and bulk to a wiping article is by combining layers of plies having different properties. U.S. Pat. No. 4,469,735 issued Sep. 4, 1984 to Trokhan discloses a multiple ply tissue paper product having a wet microcontracted constraining paper ply and a dry creped constrained paper ply. Portions of the constrained ply are adhered to the constraining ply. When the multiple ply product is wetted, unadhered portions of the constrained ply pucker in the Z-direction to provide texture and bulk. While the structure in U.S. Pat. No. 4,469,735 provides the advantage of texture and bulk upon wetting, it requires the use of wet microcontraction procedures on a paper machine. Also, the increase in caliper does not occur until wetting.
Other methods of increasing bulk and texture are known, such as embossing, creping, and laminating multiple plies of embossed, creped paper. However, these methods are limited by the amount caliper can be increased without degrading other material properties such as wet/dry strength or softness. Individual plies can generally only be mechanically deformed a certain amount before the integrity of the substrate is compromised or the aesthetic and tactile properties degraded.
Therefore, known methods of increasing caliper and texture generally rely on a wipe structure having more than one layer or ply, with differential wet extensibility providing for increased wet caliper.
Accordingly, it would be desirable to provide a single-layer disposable wiping article that exhibits regions of increased caliper without costly material and manufacturing costs associated with embossing, laminating, and similar processes.
Additionally, it would be desirable to provide a single- or multi-layer disposable wiping article having a surface topography with significant differences in maximum and minimum calipers measured within the same web.
Additionally, it would be desirable to provide a single- or multi-layer disposable wiping article having increased caliper, texture, and bulk without wetting.
Further, it would be desirable to provide a disposable wiping article having increased texture and bulk, yet retaining the softness and flexibility found in a similar article without the additional texture and bulk.
A single- or multi-ply disposable wiping article is disclosed. The disposable wiping article comprises at least one web layer and has a surface topography exhibiting regions of minimum and maximum calipers. A continuous polymer network defining bonded regions and a plurality of unbonded regions is bonded to the web layer. The continuous polymer network is preferably a thermoplastic adhesive. After curing, the thermoplastic adhesive can contract upon heating, thereby creating puckered regions of maximum caliper coincident unbonded regions. The minimum caliper of the web layer is coincident the bonded regions.
Methods of making the web of the present invention are disclosed. One method includes providing a first web layer; providing a thermoplastic adhesive; applying the thermoplastic adhesive to the first web layer in a continuous network; curing the thermoplastic adhesive; and heating the thermoplastic adhesive to effect contraction of the thermoplastic adhesive.